package com;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Scanner;

public class ReflectionTest {
    public static void main(String[] args) {
        String name;
        if(args.length > 0){
            name = args[0];
        }else {
            Scanner in = new Scanner(System.in);
            System.out.println("Enter class name (e.g. java.util.Date):");
            name = in.next();
        }

        try {
            Class cl = Class.forName(name);
            Class superclass = cl.getSuperclass();
            String modifiers = Modifier.toString(cl.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + "");
            }
            System.out.print("class " + name);
            if (superclass != null && superclass != Object.class) {
                System.out.print(" extends " + superclass.getName());
            }
            System.out.println("\n{\n");
            printConstructors(cl);
            System.out.println();
            printMethods(cl);
            System.out.println();
            printFields(cl);
            System.out.println("}");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        System.exit(0);
    }

    /**
     * prints all fields of a class
     * @param cl
     */
    private static void printFields(Class cl) {
        Field[] fields = cl.getDeclaredFields();
        for (Field field : fields) {
            Class type = field.getType();
            String name = field.getName();
            System.out.println("  ");
            String modifiers = Modifier.toString(field.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            System.out.println(type.getName() + " " + name + ";");
        }
    }

    /**
     * prints all methods of a class
     * @param cl a class
     */
    private static void printMethods(Class cl) {
        Method[] methods = cl.getDeclaredMethods();

        for (Method method : methods) {
            Class retType = method.getReturnType();
            String name = method.getName();
            System.out.println("  ");
            // print modifiers, return type and method name
            String modifiers = Modifier.toString(method.getModifiers());
            if (modifiers.length() > 0) {
                System.out.print(modifiers + " ");
            }
            System.out.println(retType.getName() + " " + name + "(");

            //print parameter types
            Class[] paramTypes = method.getParameterTypes();
            for (int j = 0; j < paramTypes.length; j++) {
                if (j > 0){
                    System.out.print(",");
                }
                System.out.println(paramTypes[j].getName());
            }
            System.out.println(")");
        }
    }

    /**
     * prints all constructors of a class
     * @param cl
     */
    private static void printConstructors(Class cl) {
        Constructor[] constructors = cl.getDeclaredConstructors();

        for(Constructor c : constructors){
            String name = c.getName();
            System.out.println("  ");
            String modifiers = Modifier.toString(c.getModifiers());
            if(c.getParameterTypes().length > 0){
                System.out.print(modifiers + " ");
            }
            System.out.println(name + "(");

            //print parameter types
            Class[] paraTypes = c.getParameterTypes();
            for(int j = 0; j < paraTypes.length; j++){
                if (j > 0){
                    System.out.print(", ");
                }
                System.out.println(paraTypes[j].getName());
            }
            System.out.println(");");
        }
    }
}
